1. Field of the Invention
The present invention relates to bowling balls and, more particularly, but not by way of limitation, to a bowling ball including an inner core of high density material which cannot be penetrated during the drilling of holes for gripping purposes or balance holes to adjust the static weight.
2. Description of the Related Art
The American Bowling Congress promulgates rules which govern the construction of bowling balls utilized by both amateur and professional bowlers. These rules contain bowling ball specifications which include the composition material of the bowling ball, which must be a non-metallic material, as well as the maximum and minimum circumference and minimum surface hardness of the bowling ball. The American Bowling Congress regulates bowling ball construction to prevent certain bowlers from gaining an unfair advantage through the use of specially designed balls.
The rule promulgated by the American Bowling Congress which allows the most flexibility in bowling ball designs relates to the non-metallic material composition of the ball. That rule provides the greatest flexibility because a variety of different materials may be used to change the performance characteristics of the ball. For example, a ball having a denser core will begin pure rolling on the bowling lane sooner than balls with less dense cores. That performance characteristic creates the desirable effect of reducing the amount of time it takes for the ball to begin spinning on the bowling lane. This increases the amount of revolution a ball achieve while rolling down the lane. A ball that commences pure rolling sooner will transfer more of its kinetic energy to the bowling pins because it loses less energy to friction.
Thus, the composition of the bowling ball becomes extremely important because the above-described rolling characteristic is produced by decreasing the ball's moment of inertia. The ball's moment of inertia is decreased by removing ball weight from the ball's outer portion and placing it in the ball's inner portion. Redistribution of the ball's weight to the center may be accomplished through the use of an inner core of dense material. Unfortunately, the densest materials (i.e., metal-based materials) are illegal due the rules promulgated by the American Bowling Congress. Accordingly, various ball designs and types of dense non-metallic materials have been employed to meet the specifications of the American Bowling Congress, while still providing a low moment of inertia for the ball.
One such bowling ball is disclosed in U.S. Pat. Nos. 4,802,671 and 5,098,096, which were issued on Feb. 7, 1989, and Mar. 24, 1992, respectively, to Gentiluomo. Gentiluomo discloses a bowling ball having a dense, spherical inner core, an annular top weight mass about the inner core, a spherical outer core, and a cover. The dense inner core is provided to increase the moment of inertia of the ball in order to increase the distance the ball travels before it begins uniform rolling motion. The decreased rolling of the Gentiluomo ball decreases the amount of kinetic energy which the ball retains as it travels down the bowling lane. The inner core disclosed in Gentiluomo is made using either a sintering process well known in the ceramic art or by cold pressing bonding resins mixed with powdered ceramics or minerals into a spherical core.
Although the dense inner core provides an improvement in the stabilization of the ball, the spherical construction of both the inner and outer cores creates the control problem of allowing a breakpoint in the path of the ball's travel at a point relatively early along the bowling lane. That is, once the ball begins uniform rolling, any rotation imparted to the ball by the bowler will immediately produce a hook in the ball's path of travel because the spherical shape of both the inner and outer cores provides no counterweight to offset the rotation of the ball. Thus, a consistent hook in the ball's path of travel at the back end of the bowling lane which is essential to scoring well is extremely difficult to achieve. The only way to achieve a late breaking hook is for the bowler to impart a tremendous amount of spin to the ball which defeats the purpose of producing a ball having a low moment of inertia and, further, makes control of the bail extremely difficult. Accordingly, even though the Gentiluomo bowling ball produces improved stabilizing characteristics, its hooking action at a point early along the bowling lane provides less than satisfactory control of the breakpoint and less than satisfactory transfer of energy.
Accordingly, a bowling ball that provides increased kinetic energy by rolling sooner at the front end of the lane while still producing a sharp break at the back end of the lane is highly desirable.